This paper explores the importance of elements of the natural world, and particularly plants, among people of different religious affiliations in western Africa. Plants play an overriding role in African folk religions, which in turn are closely associated with health practices and influence management decisions concerning natural resources. In spite of the extensive literature documenting ritual plant use, the cultural importance of plants in this context has not been systematically assessed. Our objective was to see whether the importance of plants was reflected in people’s conceptions of global (i.e., Christianity, Islam) and folk religions (i.e., Vodoun and Bwiti) in Benin (West Africa) and Gabon (Central Africa). By performing a cultural domain analysis (CDA) with 96 individuals, we found that, regardless of the religious affiliation of informants, plants and other elements of the natural world were more present in people’s notions of folk religions than in global religions. We conclude by reflecting on the potentials and limitations of the data presented here as a starting point to explore the topic of cultural keystone species.